This publication applies to air separation and cryogenic liquefaction plants in which the venting of oxygen, nitrogen, oxygen/nitrogen mixtures, argon, or air occurs.

Disposal of cryogenic liquid is not covered in this publication although the potential for vent releases to have some liquid present is included.

The recommendations contained in this publication for elevations and horizontal separation distances are not applicable to customer station tanks. Safety distances for such tanks are governed by the design criteria for plant layout or national regulations/codes of practice, whichever are more stringent.

This publication is designed to give a basis on which to determine the safe location of oxygen or nitrogen and argon gas vents for normal operating, upset, and emergency conditions. This determination can be made by calculation against the criteria specified or by use of the tables provided in the appendices as a guide.

The publication contains calculated safe separation distances for a range of vent sizes and orientations based on commonly encountered but specific design conditions. If these design criteria are not met particularly with regard to vents intended to operate over a large range of flows (for example, product vents having turndown flows), the tables may not be appropriate and detailed calculations should be carried out.

This publication should be used for new designs but can be used on existing plants to determine whether existing vents are safely located or whether modifications/temporary structures will interfere with the original design intent.